1. Field of the Invention
The present invention relates to the field of downhole fluid analysis in hydrocarbon producing wells for determining fluid density, viscosity, and other parameters for a fluid downhole in a borehole during monitoring while drilling or wire line operations. More particularly, the present invention relates to a method and apparatus for insulating electrical connections to a resonator from conductive fluid downhole.
2. Background Information
U.S. Pat. No. 6,938,470 by DiFoggio et al. describes a downhole method and apparatus for using a mechanical resonator, for example, a tuning fork to provide real-time direct measurements and estimates of the viscosity, density and dielectric constant of formation fluid or filtrate in a hydrocarbon producing well. As shown generally in DiFoggio et al. (U.S. Pat. No. 6,938,470), a resonator, such as a piezoelectric tuning fork is placed downhole as an addition to a fluid analyzer module.
One obstacle to the successful use of resonators such as tuning forks downhole has been electrical shorting of resonator electrical connections when exposed to conductive fluids downhole. Downhole fluids are under the extreme pressure and temperature encountered downhole. Downhole pressure can exceed 30,000 pounds per square inch (PSI) and temperature can exceed 350° F. Fluid downhole under high pressure and temperature can force downhole fluid into the electrical insulation around a resonator and short out the electrical connections to the resonator.